Rolling element accommodating belt for linear guide apparatus, linear guide apparatus and metallic mold for manufacturing rolling element accommodating belt

ABSTRACT

The metallic mold  90  includes a product configuration portion  93  formed between an upper mold  91  and a lower mold  92 . This product configuration portion  93  is composed so that a rolling element accommodating belt  50  formed by this product configuration portion  93  can include spacer portions interposed between balls adjacent to each other in an infinite circulating passage and also include connecting arm portions for connecting the spacer portions to each other and so that the balls can be aligned in the alignment direction in the infinite circulating passage. The upper mold  91  has a splitting structure. In this splitting structure, a splitting position BL is set at a position passing through a position  91   t  for forming an end portion on the outer circumferential side in the inner and outer circumferential direction of the infinite circulating passage of the spacer portions  51.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a rolling element accommodating belt, alinear guide apparatus and a metallic mold for manufacturing the rollingelement accommodating belt.

2. Description of Related Art

In the linear guide apparatus, a slider is relatively moved with respectto a guide rail through a plurality of rolling elements which arerolling and circulating in an infinite circulating passage. However, inthe linear guide apparatus, while the slider is relatively moving withrespect to the guide rail, the rolling elements are rolling and moved inthe same direction. Therefore, the rolling elements, which are adjacentto each other, are rubbed to each other. Accordingly, the rollingelements can not be smoothly rolled. Therefore, an intensity of noise isincreased and abrasion of the rolling elements is facilitated. In orderto solve the above problems by suppressing the generation of noise andmaking the linear guide apparatus operated smoothly, a rolling elementaccommodating belt is conventionally proposed in which the rollingelements are aligned in the alignment direction in the infinitecirculating passage so as to smoothly operate the linear guideapparatus. Concerning this rolling element accommodating belt, forexample, refer to Japanese Patent Unexamined Publications JP-A-05-52217,JP-A-2001-165169, JP-A-10-9264, JP-A-09-14264, JP-A-11-247856 andJP-A-2005-69444.

For example, according to the JP-A-05-52217, JP-A-2001-165169 andJP-A-10-9264, a rolling element accommodating belt is disclosed whichincludes spacer portions interposed between the rolling elementsadjacent to each other and also includes connecting arm portions forconnecting the spacer portions. According to the rolling elementaccommodating belt composed as described above, the rolling elements arealigned in a line in the alignment direction in the infinite circulatingpassage so as to suppress the generation of noise so that the rollingelements can be smoothly circulated in the infinite circulating passage.In this connection, according to the technique described in theJP-A-2001-165169, the rolling element accommodating belt is composed insuch a manner that the rolling elements accommodated on the rollingelement accommodating belt can be freely detached in a perpendiculardirection to the front and the back surface of the rolling elementaccommodating belt.

This type rolling element accommodating belt is obtained when meltedresin material is poured from a gate into a product configurationportion in a metallic mold. However, in the product configurationportion in the metallic mold, residual air and gas, which is generatedfrom the melted resin material, exists. These gases tend to stay in aportion where a gas flowing passage comes to a dead end. Especially,these gases tend to stay in an end portion of the above spacer portion.Therefore, it is difficult for the melted resin to smoothly flow intothis portion where the gases are staying. Accordingly, an underfillportion of resin (which is a portion where predetermined amount of resinis not filled) is generated on the rolling element accommodating beltformed in the mold. When the underfill portion of resin is generated inthis way, there is a possibility that damage starts from this underfillportion of resin generated on the rolling element accommodating belt.

In this case, for example, according to the technique described in theJP-A-11-247856 or JP-A-2005-69444, a joint portion of the upper mold andthe lower mold of the metallic mold can be made to function as a gasvent. However, at the end portion of the formed spacer portion, no meansis provided for discharging gas. Therefore, gas tends to stay at the endportion of the formed spacer portion. Therefore, the spacer portionneeds to be more investigated to discharge gas so that the generation ofan under fill portion of resin can be prevented.

Further, concerning the method of manufacturing this type rollingelement accommodating belt, for example, the JP-A-05-52217 discloses atechnique in which the rolling elements are arranged in a metallic moldso that the rolling elements can be used as a core and then injectionmolding is conducted to manufacture the rolling element accommodatingbelt.

The JP-A-09-14264 discloses a technique in which injection molding isconducted while the rolling elements are being used as a core in thesame manner as that described above. However, in order to solve aproblem that a portion, in which the rolling elements are accommodated,and the rolling elements are tightly contacted with each other by theshrinkage caused at the time of forming, oil or water is absorbed afterthe completion of molding.

Another manufacturing method is disclosed in the JP-A-11-247856 asfollows. For example, in the JP-A-11-247856, rolling elementshaped-molds, the sizes of which are larger than the diameters of therolling elements to be used, are arranged at predetermined intervals andinjection molding is conducted to manufacture a rolling elementaccommodating belt.

The JP-A-2005-69444 discloses a technique in which a formed rollingelement accommodating belt is detached from a metallic mold by obliquelymoving the metallic mold used in the injection molding. In this case, inthe examples disclosed in the JP-A-11-247856 and JP-A-2005-69444, aposition of a dividing line of an upper mold and a lower mold is locatedat a peripheral portion of a spacer portion. Concerning this matter,refer to FIG. 2 of the JP-A-11-247856 and FIG. 9 of JP-A-2005-69444.

However, in the above method of manufacturing the rolling elementaccommodating belt, for example, in the technique described in theJP-A-05-52217 in which injection molding is conducted while the rollingelements are being used as a core, due to the shrinkage of materialcaused at the time of forming, sizes of portions, in which the rollingelements are accommodated, are reduced smaller than the predeterminedsizes. Therefore, the rolling elements can not be smoothly rolled.

For example, in the technique described in the JP-A-09-14264, in orderto avoid a case where the rolling elements can not be smoothly rolledbecause of the shrinkage caused at the time of forming, the processingof absorbing oil or the processing of absorbing water is conducted afterthe completion of forming. In this case, it is necessary to strictlycontrol the conditions of processing of absorbing oil or absorbingwater, which raises the manufacturing cost.

For example, in the technique described in the JP-A-11-247856, in thespacer portion which has been formed, a concave face corresponding tothe circumferential face of the rolling element mold is formed as anunder-cut portion. Therefore, when the rolling element belt is detachedfrom the metallic mold, a strong force is given to the rolling elementaccommodating belt. Accordingly, there is a possibility that the rollingelement accommodating belt is damaged or deformed.

Further, in the technique described in the JP-A-11-247856 and theJP-A-2005-69444, a position of the dividing line of the upper and thelower mold of the metallic mold is located in the peripheral portion ofthe spacer portion. Accordingly, burr is generated in the peripheralportion of the spacer portion. Due to the generation of burr, there is apossibility that the linear guide apparatus can not be smoothlyoperated. That is, at the time of forming, resin flows into a jointportion of the upper mold and the lower mold, which causes thegeneration of burr. In the case where this burr is generated in theperipheral portion of the spacer portion, when the rolling elementaccommodating belt circulates in the infinite circulating passage of thelinear guide apparatus, the rolling element accommodating belt rubs aninner circumferential wall of the infinite circulating passage.Alternatively, the rolling element accommodating belt is hooked on theinner circumferential wall of the infinite circulating passage.Therefore, there is a possibility that a smooth operation of the linearguide apparatus is obstructed.

In the case of the rolling element accommodating belt disclosed inJP-A-2001-165169, the rolling elements accommodated there can be freelydetached in a direction perpendicular to the surface side and the backside of the rolling element accommodating belt. For example, asexemplarily shown in FIG. 17, a position of the dividing line of themetallic mold of the spacer portion is formed while crossing a faceincluding a portion coming into contact with the rolling elements. Whenthe dividing line of the metallic mold is set at this position, burr isnot generated in the periphery of the spacer portion, however, burr isgenerated in a portion coming into contact with the rolling elements.Therefore, by the burr protruding onto the rolling element side, theface, which is to be contacted with the rolling elements, and therolling elements can not be stably contacted with each other.Accordingly, smooth operation of the linear guide apparatus isobstructed. In order to prevent the above generation of burr, it isnecessary to enhance the accuracy of the joint face of the metallicmold. Alternatively, it is necessary to severely control the formingcondition. However, when the above countermeasures are taken, themanufacturing cost is raised.

SUMMARY OF THE INVENTION

In view of the above, one object of the present invention is to providea metallic mold for manufacturing a rolling element accommodating beltin which the forming of the underfill portion is prevented or refrained,a rolling element accommodating belt for a linear guide apparatusmanufactured by the metallic mold, and a linear guide apparatus providedwith thus obtained rolling element accommodating belt.

Further, another object of the invention is to provide a rolling elementaccommodating belt for a linear guide apparatus, the linear guideapparatus and a metallic mold for manufacturing the rolling elementaccommodating belt capable of smoothly circulating the rolling elementaccommodating belt even when the burr is generated.

According to a first aspect of the invention, there is provided ametallic mold for injection molding a rolling element accommodating beltfor a linear guide apparatus, which has an infinite circulating passagein which a plurality of rolling elements are rolling and circulating,the rolling element accommodating belt including:

a spacer portion interposed between the rolling elements adjacent toeach other; and

a connecting arm portion for connecting the spacer portions to eachother, wherein

the rolling elements are aligned in the infinite circulating passage inan alignment direction,

the metallic mold including:

an upper mold;

a lower mold; and

a product configuration portion provided between the upper mold and thelower mold, wherein

the rolling element accommodation belt is molded within the productconfiguration portion, and

at least one of the upper and the lower mold has a splitting structurein which a splitting position is located at a position where an endportion of at least one side of inner and outer circumferentialdirection of the infinite circulating passage of the spacer portion isformed.

According to the first aspect of the invention, a splitting position ofa metallic mold is set at a position passing through a position forforming an end portion on at least one side in the inner and outercircumferential direction of the infinite circulating passage of thespacer portion. Therefore, a joint portion of the splitting position ofthe metallic mold can be made to function as a gas vent at the endportion of the spacer portion. Therefore, it is possible to prevent orsuppress gas from staying in the end portion of the spacer portion inwhich gas tends to stay. Accordingly, it becomes possible for the resinto flow to the end portion of the spacer portion. Consequently, theunderfill of resin caused at the time of forming can be prevented orsuppressed.

According to a second aspect of the invention, there is provided arolling element accommodating belt manufactured by the metallic mold asset forth in the first aspect of the invention.

According to the second invention, the rolling element accommodatingbelt is manufactured by the metallic mold for manufacturing the rollingelement accommodating belt of the first invention. Therefore, it ispossible to provide a rolling element accommodating belt on which thegeneration of an underfill portion of resin, which is caused in the endportion of the spacer portion at the time of forming, can be suitablyprevented.

According to a third aspect of the invention, there is provided arolling element accommodating belt for a linear guide apparatus, whichhas an infinite circulating passage in which a plurality of rollingelements are rolling and circulating, the rolling element accommodatingbelt including:

a spacer portion interposed between the rolling elements adjacent toeach other; and

a connecting arm portion for connecting the spacer portions to eachother, wherein

the rolling elements are aligned in the infinite circulating passage inan alignment direction,

the rolling element accommodation belt is formed by injection molding byusing a metallic mold having splitting structure, and

a parting line of the metallic mold is transferred to an end portion onat least one side of inner and outer circumferential direction of theinfinite circulating passage in the spacer portion.

According to the third aspect of the invention, the rolling elementaccommodating belt for a linear guide apparatus of the present inventionis provided. Therefore, it is possible to provide a linear guideapparatus provided with a rolling element accommodating belt, thequality of which is stabilized, having no underfill portion of resin inthe spacer portion.

According to a sixth aspect of the invention, there is provided arolling element accommodating belt for a linear guide apparatus, whichhas an infinite circulating passage in which a plurality of rollingelements are rolling and circulating, the rolling element accommodatingbelt including:

a spacer portion interposed between the rolling elements adjacent toeach other; and

a connecting arm portion for connecting the spacer portions to eachother, wherein

the rolling elements are aligned in the infinite circulating passage inan alignment direction, and

a face of each spacer portion directed to the rolling element includes:

-   -   a non-contact face which does not contact with the rolling        element; and    -   a contact face which is hollow with respect to the non-contact        face and contacts with the rolling element.

According to the sixth aspect of the invention, the spacer portionincludes: a non-contact face on which a face of the spacer portiondirected to the adjacent rolling element side is not contacted with theadjacent rolling element; and a contact face on which a face of thespacer portion directed to the adjacent rolling element side iscontacted with the adjacent rolling element. Therefore, for example, adividing line of the metallic mold can be set on the non-contact face.Due to the foregoing, with respect to the circumferential edge portionof the spacer portion and with respect to the contact face having aportion coming into contact with the rolling element, while the dividingline of the metallic mold is not being provided, the rolling elementaccommodating belt can be composed. Therefore, even in the case whereburr is generated at a position of the joint portion of the metallicmold, it is possible to prevent the burr from rubbing an innercircumferential wall of the infinite circulating passage. Further, it ispossible to prevent the burr from being hooked on the innercircumferential wall of the infinite circulating passage. Furthermore,there is no possibility that a stable contacting state of the contactface with the rolling elements is deteriorated. Accordingly, even whenburr is generated, the rolling element accommodating belt can besmoothly circulated. When countermeasures are taken in order to preventthe generation of burr, it is possible to mitigate the degree ofenhancing the accuracy of the joint portion of the metallic mold. It isalso possible to mitigate the degree of controlling the formingcondition. Therefore, the manufacturing cost can be reduced.

In the case of the rolling element accommodating belt related to thesixth aspect of the invention, it is preferable that the non-contactface is formed into a plane perpendicular to the alignment direction inthe infinite circulating passage. Due to the above structure, when areleasing direction of the upper and the lower mold is set in thedirection in which the non-contact face is formed, releasing can beeasily executed.

In the case of the rolling element accommodating belt related to thesixth aspect of the invention, the rolling element accommodatingportions for individually accommodating the rolling elements are definedby the spacer portions and the connecting arm portions. It is preferablethat the rolling element accommodating portions are formed so that therolling elements accommodated there can be allowed to move at least toone side in the inner and the outer circumferential direction of theinfinite circulating passage. Due to the above structure, when therolling element accommodating belt is pushed with pushing pins from aside on which the rolling elements are allowed to move after the rollingelement accommodating belt has been formed in the metallic mold, it ispossible to release the rolling element accommodating belt from a sideon which no undercut is formed. Therefore, releasing can be conductedwithout giving an extremely strong force to the rolling elementaccommodating belt.

In the case of the rolling element accommodating belt related to thesixth aspect of the invention, the rolling element accommodating belt isformed of synthetic resin by injection molding with the metallic mold,between the upper mold and the lower mold of which the productconfiguration portion for forming the rolling element accommodating beltconcerned is provided. It is preferable that the dividing line of theupper mold and the lower mold is formed on the non-contact face of thespacer portion or on the boundary between the non-contact face and thecontact face. Due to the above structure, the rolling elementaccommodating belt can be composed without providing a dividing line ofthe metallic mold with respect to the peripheral portion of the spacerportion and with respect to the contact face having a portion cominginto contact with the rolling element. Accordingly, even when burr isgenerated, the rolling element accommodating belt can be smoothlycirculated. When the dividing line of the upper mold and the lower moldis provided on the boundary between the non-contact face and the contactface, the structure of the upper and the lower mold can be moresimplified.

According to a seventh aspect of the invention, there is provided alinear guide apparatus including a rolling element accommodating belt asset forth in the sixth aspect of the invention.

According to the seventh aspect of the invention, it is possible toprovide a linear guide apparatus by which an action and advantageprovided by the rolling element accommodating belt for a linear guideapparatus of the sixth aspect of the invention can be provided.

According to an eleventh aspect of the invention, there is provided ametallic mold for manufacturing the rolling element accommodating beltaccording to claim 6 by injection molding, the metallic mold including:

an upper mold; and

a lower mold, wherein

a product configuration portion for forming the rolling elementaccommodating belt is formed between the upper mold and the lower mold,and

the upper mold and the lower mold are divided on a position where thenon-contact face of the spacer portion or on a boundary between thenon-contact face and the contact face is formed.

According to the eleventh aspect of the invention, it is possible toprovide a metallic mold for manufacturing a rolling elementaccommodating belt preferably used for manufacturing the rolling elementaccommodating belt for a linear guide apparatus of the first invention.

As described above, according to the present invention, it is possibleto provide a metallic mold for manufacturing a rolling elementaccommodating belt capable of preventing or suppressing an underfillportion of resin generated at the time of forming. It is also possibleto provide a rolling element accommodating belt for a linear guideapparatus manufactured by the metallic mold. It is also possible toprovide a linear guide apparatus provided with the rolling elementaccommodating belt.

Further, according to the present invention, it is possible to provide arolling element accommodating belt for a linear guide apparatus capableof smoothly circulating the rolling element accommodating belt even whenburr is generated. It is also possible to provide the linear guideapparatus and a metallic mold for manufacturing the rolling elementaccommodating belt.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a linear guide of the firstembodiment of the present invention;

FIG. 2 is a front view showing the linear guide of FIG. 1 from which anend cap has been removed;

FIG. 3 is a view for explaining the linear guide of the presentinvention. FIG. 3 is a sectional view taken on line X-X of the linearguide shown in FIG. 2;

FIG. 4A is a view for explaining a rolling element accommodating belt ofthe present invention;

FIG. 4B is a view for explaining a rolling element accommodating belt ofthe present invention;

FIG. 4C is a view for explaining a rolling element accommodating belt ofthe present invention;

FIG. 5A is a perspective view showing only the inner side of a splitupper mold of the metallic mold of the invention and also showing asplit lower mold which is cut in the longitudinal direction of a rollingelement accommodating belt to be formed;

FIG. 5B is a perspective view of a product configuration portion of theupper mold of the metallic mold;

FIG. 5C is a perspective view showing a product configuration portion ofthe lower mold of the invention;

FIG. 6A is a perspective view showing a split inner side of the metallicmold of the invention;

FIG. 6B is a perspective view showing a split viewer's side of themetallic mold of the invention;

FIGS. 7A to 7D are schematic illustrations for explaining a forming stepin which a rolling element accommodating belt is formed by a metallicmold for manufacturing a rolling element accommodating belt of thepresent invention;

FIG. 8A is an enlarged view showing a primary portion of FIG. 7C andalso showing a model of a flow of resin in the case of pouring the resininto a product configuration portion of a metallic mold;

FIG. 8B is a perspective view showing a splitting portion of a metallicmold transferred onto the formed rolling element accommodating belt;

FIG. 9A is a view for explaining a metallic mold of Comparative Exampleand is corresponding to FIG. 5B of the first embodiment;

FIG. 9B is a view corresponding to FIG. 8A;

FIG. 9C is a view corresponding to FIG. 8B;

FIG. 10A is a view showing a product configuration portion of the lowermold of the metallic mold according to the first modification;

FIGS. 10B and 10C are views respectively showing an inner side and aviewer's side of the split lower mold;

FIG. 11A is a perspective view showing a product configuration portionof the upper mold of the metallic mold according to the secondmodification;

FIG. 11B is a view corresponding to FIG. 8A;

FIG. 12 is a perspective view showing a splitting portion of a metallicmold transferred onto a formed rolling element accommodating beltaccording to the second modification;

FIG. 13A is a perspective view of a metallic mold of the secondembodiment of the present invention which has been cut in thelongitudinal direction of a rolling element accommodating belt to beformed;

FIG. 13B is a perspective view of a product configuration portion of anupper mold of the metallic mold according to the second embodiment;

FIG. 13C is a perspective view of a product configuration portion of alower mold of the metallic mold according to the second embodiment;

FIG. 14A is a schematic illustration for explaining a forming stepexecuted by a metallic mold for manufacturing a rolling elementaccommodating belt of the present invention;

FIG. 14B is a schematic illustration for explaining a forming stepexecuted by a metallic mold for manufacturing a rolling elementaccommodating belt of the present invention;

FIG. 14C is a schematic illustration for explaining a forming stepexecuted by a metallic mold for manufacturing a rolling elementaccommodating belt of the present invention;

FIG. 14D is a schematic illustration for explaining a forming stepexecuted by a metallic mold for manufacturing a rolling elementaccommodating belt of the present invention;

FIG. 15 is a schematic illustration for explaining a position of adividing line on a rolling element accommodating belt of the presentinvention;

FIG. 16A is a view for explaining a linear guide of the third embodimentcorresponding to FIG. 4C of the second embodiment;

FIG. 16B is a view for explaining a linear guide of the third embodimentcorresponding to FIG. 14B; and

FIG. 17 is a schematic illustration for explaining an example of aposition of a dividing line between an upper mold and a lower mold of aconventional rolling element accommodating belt.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTIONEMBODIMENTS

Appropriately referring to the drawings, embodiments of the rollingelement accommodating belt for a linear guide apparatus of the presentinvention, the linear guide apparatus provided with the rolling elementaccommodating belt and the metallic mold for manufacturing the rollingelement accommodating belt will be explained below.

First Embodiment

At first, the first embodiment of the present invention according to thefirst to fifth aspects of the invention will be explained.

FIG. 1 is a perspective view showing a linear guide of the firstembodiment of a linear guide apparatus having a rolling elementaccommodating belt of the present invention. FIG. 2 is a front viewshowing the linear guide of FIG. 1 from which an end cap has beenremoved. FIG. 3 is a sectional view taken on line X-X of the linearguide shown in FIG. 2.

As shown in FIGS. 1 and 2, this linear guide 10 includes: a guide rail12 having a rolling element guide face 14; and a slider 16 mounted onthe guide rail 12 so that the slider 16 can be relatively moved withrespect to the guide rail 12.

The guide rail 12 has a substantially square cross section. On bothsides of the guide rail 12, four rolling element guide faces 14 areprovided, that is, two rolling element guide faces 14 are provided onone side of the guide rail 12 and two rolling element guide faces 14 areprovided on the other side. These rolling element guide faces 14 arelinearly formed in the longitudinal direction of the guide rail 12.

As shown in FIG. 1, the slider 16 includes: a slider body 17; and endcaps 22 respectively attached to both end portions in the axialdirection of the slider body 17. Cross sections of both the slider body17 and end caps 22 in the axial direction are C-shapes.

As shown in FIG. 2, in the slider body 17, four loaded rolling elementguide faces 18, the cross sections of which are substantiallysemicircular, are formed on the inside of both sleeve portions, theshapes of which are formed into C-shape, wherein the four loaded rollingelement guide faces 18 are respectively opposed to the rolling elementguide faces 14 of the guide rail 12. As shown in FIG. 3, a pair ofdirection changing passages 24, which are respectively connected to bothend portions of the loaded rolling element guide face 18, are formed inthe end cap 22. As shown in FIGS. 2 and 3, inside the sleeve portion ofthe slider body 17, a rolling element return passage 20, is formed,which is communicated with the pair of direction changing passages 24and formed out of a circular through-hole parallel with the loadedrolling element guide face 18. A space interposed between the rollingelement guide face 14 of the guide rail 12 and the loaded rollingelement guide face 18 of the slider body 17, which is opposed to therolling element guide face 14, is a rolling element passage 26. Fourannular continuous infinite circulating passages 28 are formed out of apair of direction changing passages 24, the rolling element returnpassage 20 and the rolling element passage 26. Further, into theinfinite circulating passages 28, a plurality of balls 46, which arerolling elements, are charged. The plurality of balls 46 charged intoeach infinite circulating passages 28 compose a row 62 of rollingelements by the rolling element accommodating belt 50 together with therolling element accommodating belt 50.

Appropriately referring to FIGS. 3 and 4, this rolling elementaccommodating belt 50 will be explained below in more detail. FIG. 4 isa schematic illustration for explaining the rolling elementaccommodating belt. FIG. 4A is a perspective view of the rolling elementaccommodating belt, wherein the view is taken from the outercircumference side of the infinite circulating passage. FIG. 4B is aperspective view of the rolling element accommodating belt, wherein theview is taken from the inner circumference side of the infinitecirculating passage. FIG. 4C is a sectional view of the rolling elementaccommodating belt, wherein the view is taken in the alignment directionof the balls.

As shown in FIG. 3, this rolling element accommodating belt 50 is formedbeing provided with end portions. This rolling element accommodatingbelt 50 includes: spacer portions 51 interposed between the balls 46which are adjacent to each other in the infinite circulating passage 28;and connecting arm portions 52 for connecting the spacer portions 51with each other. These spacer portions 51 and the connecting armportions 52 are integrally formed out of synthetic resin, which is aflexible, extensible, elastic material, by means of injection molding.An example of this synthetic resin material is a flexible thermoplasticmaterial such as polyester elastomer and polyurethane.

As shown in FIG. 3, the connecting arm portions 52 are thin, long andbelt-shaped members. As shown in FIG. 4, the ball accommodating holes58, which are circular through-holes for accommodating the balls 46, areformed being arranged in the longitudinal direction. Inner diameters ofthese ball accommodating holes 58 are formed so that the balls 46 can befreely engaged in and disengaged from the ball accommodating holes 58 inthe direction of the surface side and the back side of the connectingarm portions 52.

As shown in FIG. 4, the spacer portions 51 are arranged on both sides ofthe ball accommodating holes 58 in the alignment direction of the balls46 with respect to the connecting arm portions 52. These spacer portion51 are short columnar members, the outer diameters of which are a littlesmaller than the outer diameters of the balls 46. The axis of the shortcolumnar shape agrees with the longitudinal direction of the rollingelement accommodating belt 50. The spacer portions 51 are arranged onboth sides of the ball accommodating holes 58 at predetermined intervalsand connected to each other by the connecting arm portion 52 at bothsides in the width direction of the infinite circulating passage 28.Both end portions of the short columnar shapes are formed to be faces 54directed to the adjacent balls 46 in the infinite circulating passage28.

On this rolling element accommodating belt 50, a space defined by eachspacer portion 51 and the ball accommodating hole 58 of the connectingarm portion 52 is formed into the rolling element accommodating portion59. When the balls 46 are individually accommodated in these rollingelement accommodating portions 59 and aligned in the alignment directionin the infinite circulating passage 28, a row of rolling elements 62 canbe composed. As shown in FIG. 2, on this rolling element accommodatingbelt 50, the connecting arm portions 52 are respectively protruded onboth sides in the width direction in the infinite circulating passage28. The thickness of the connecting arm portions 52 is a little smallerthan the groove width of the guide groove 60, that is, the thickness ofthe connecting arm portions 52 is determined to be thin as long as thesufficiently and necessarily high mechanical strength can be maintained.These connecting arm portions 52 are slidably engaged in the guidegroove 60 so that the connecting arm portions 52 can be guided on bothsides in the width direction of the infinite circulating passage 28. Inthis connection, as shown in FIG. 3, on this rolling elementaccommodating belt 50, two end portions 57 respectively located at bothends the rolling element accommodating belt 50 are opposed to each otherin the infinite circulating passage 28 being not contacted with eachother. Between the end portions 57 opposed to each other, one ball 46 ischarged.

As shown in FIG. 4, on this rolling element accommodating belt 50, theface 54 of the spacer portion 51 directed to the adjacent ball 46 sideincludes: a no-contact face 55 which is not contacted with the adjacentball 46; and a contact face 56 which is formed becoming hollow withrespect to the no-contact face 55.

To be in detail, the no-contact face 55 is formed into a plane which isarranged in a direction perpendicular to the alignment direction of theballs in the infinite circulating passage 28. On the other hand, thecontact face 56 is formed into a face having a portion coming intocontact with the spherical face of the ball 46 which is a rolling face.In the example of the present embodiment, each contact face 56 includes:a side portion 56 b formed out of a recessed cylindrical face extendingto the outer circumferential side by the same width; and an inclinedface portion 56 a which is a recessed conical face, the width of whichis increased toward the end portion on the inner circumferential side.

The contact faces 56 of the spacer portions 51, which are opposed toeach other in the alignment direction, are formed into a pair.Therefore, the spacer portions 51 can hold the balls 46 so that theballs 46 can be freely rolled while the balls 46 in the rolling elementaccommodating portions 59 can be moved onto the outer circumferentialside of the infinite circulating passage 28 and restricted toward theinner circumferential side.

That is, as shown in FIG. 4C, the contact faces 56 of the spacerportions 51, which are adjacent to each other, are formed into a pair. Adistance TW between the side portions 56 b opposed to each other of thepair of contact faces 56 is the same as the inner diameter of the ballaccommodating hole 58. Therefore, the ball 46 accommodated in each ballaccommodating hole 58 can be allowed to move toward the outercircumferential side of the infinite circulating passage 28. On theother hand, the inclined face portions 56 a of the pair of contact faces56 are formed into recessed conical faces coming into contact with theball by a predetermined inclined angle with respect to the alignmentdirection. Therefore, the ball 46 accommodated in each ballaccommodating hole 58 is restricted from moving toward the innercircumferential side of the infinite circulating passage 28.

In the thus composed linear guide 10, when the slider 16 is relativelymoved in the axial direction of the guide rail 12 while the balls 46 arerolling in the infinite circulating passage 28, the rolling elementaccommodating belt 50 is also moved in the infinite circulating passage28 together with the balls 46. At this time, in the infinite circulatingpassage 28, the spacer portion 51 of the rolling element accommodatingbelt 50 pushes the ball 46 located in the front in the moving direction.Further, the ball 46 pushes the spacer portion 51 located in the frontin the moving direction. Due to the foregoing, the entire rollingelement row 62 circulates in the infinite circulating passage 28. Therolling element row 62 is moved in the opposite direction to the slider16 in the rolling element passage 26. The rolling element row 62 entersfrom one end portion of the rolling element passage 26 into onedirection changing passage 24 so that the moving direction of therolling element row 62 can be changed. The rolling element row 62 entersfrom the direction changing passage 24 into the rolling element returnpassage 20 and moves in the same direction as that of the slider 16. Therolling element row 62 enters into the other direction changing passage24 so that the moving direction can be changed again. Then, the rollingelement row 62 returns to the rolling element passage 26. The abovecirculation of the rolling element row 62 can be repeated. Theconnecting arm portion 52 of each rolling element accommodating belt 50is engaged with the guide groove 60. Therefore, it is possible toprevent each spacer portion 51 from falling down in the rolling elementpassage 26. Further, it is possible to prevent an arrangement of therolling element row 62 from being disturbed, that is, it is possible toprevent a smooth movement of the rolling element row 62 from beingobstructed. Since the connecting arm portion 52 of the rolling elementaccommodating belt 50 is guided by the infinite circulating passage 28along the guide groove 60, deviation of the rolling elementaccommodating belt 50 is restricted while it is moving. Further,deviation of the ball 46 held between the connecting arm portions 52 ofthe rolling element accommodating belt 50 is also restricted. Therefore,the entire rolling element row 62 can be accurately, smoothly moved inthe infinite circulating passage 28.

In this case, the above rolling element accommodating belt 50 ismanufactured by means of injection molding with the metallic mold shownin FIG. 5.

Referring to FIGS. 5 to 7, explanations will be made into the metallicmold, which is used for manufacturing the rolling element accommodatingbelt 50, and the manufacturing step of injection molding in which thismetallic mold is used. In this connection, injection molding isconducted according to a conventional method. Therefore, only an outlineof injection molding will be described here.

Steel products are used for the metallic mold which is a form forforming this rolling element accommodating belt 50. As shown in FIG. 5,this metallic mold 90 includes: an upper mold 91 which is a movable sidemetallic mold; and a lower mold 92 which is a stationary side metallicmold. The upper mold 91 and the lower mold 92 are arranged being opposedto each other as shown in FIG. 6A. As shown in FIG. 7, a gap portiondefined between the upper mold 91 and the lower mold 92 is a productconfiguration portion (cavity) 93.

A configuration of the product configuration portion 93 formed betweenthe upper mold 91 and the lower mold 92 is formed when a configurationof the rolling element accommodating belt 50, which is a product, isinverted so that a relation between male and female can be inverted.Further, a size of the product configuration portion 93 is decided whenconsideration is given to a deformation generated in the step ofinjection molding.

That is, as shown in FIG. 5, the configuration of this metallic mold 90is formed when the configuration of the rolling element accommodatingportion 59 is inverted so that the relation between male and female canbe inverted. In the upper mold 91, a plurality of protruded truncatedcone portions 91 a are formed in the longitudinal direction in the uppermold 91. On the other hand, in the lower mold 92, a plurality ofrecessed truncated cone portions 92 a are formed which are arrangedbeing opposed to the protruded truncated cone portions 91 a of the uppermold 91 and agree with the protruded truncated cone portions 91 a sothat the recessed truncated cone portions 92 a can be engaged with theprotruded truncated cone portions 91 a.

In the upper mold 91, in the periphery on the base end side of theprotruded truncated cone portions 91 a, a plane portion 91 m for formingthe connecting arm portion 52 is formed. In the lower mold 92, in theperiphery on the side on which the recessed truncated cone portion 92 ais open, a plane portion 92 m is formed which forms the connecting armportion 52 together with the plane portion 91 m. Further, in thelongitudinal direction of the metallic mold 90, in the upper mold 91,recess portions 91 c for forming the spacer portions 51 are formed onboth sides of the protruded truncated cone portion 91 a. On the otherhand, in the lower mold 92, recess portions 92 c for forming the spacerportions 51 are formed on both sides of the recessed truncated coneportions 92 a. Configurations of these portions are formed intoconfigurations obtained when configurations of the spacer portions 51are inverted.

The contact face 56 of the spacer portion 51 is formed by the inclinedportion 91 d of the protruded truncated cone portion 91 a of the uppermold 91 and by the protruded cylindrical portion 91 b formed in therecessed portion 91 c for forming the spacer portion 51. The no-contactface 55 of the spacer portion 51 is formed by the plane portion 91 fwhich is formed in the recessed portion 91 c of the upper mold 91 anddirected in the longitudinal direction and by the plane portion 92 fwhich is formed in the recessed portion 92 c of the lower mold 91 anddirected in the longitudinal direction. In this connection, directionsof the plane portions 91 f and 92 f are set so that no-contact face 55of the formed rolling element accommodating belt 50 can be a planeformed in a direction perpendicular to the alignment direction of theinfinite circulating passage 28. Further, releasing directions of theupper mold 91 and the lower mold 92 are set in a direction in whichno-contact face 55 is formed. A splitting position between the uppermold 91 and the lower mold 92 is located close to the lower mold 92. Theend portion 51 n on the inner circumferential side of the spacer portion51 is located in the neighborhood of the lower mold 92.

In this case, as shown in FIGS. 5B and 6, this upper mold 91 has asplitting structure in which the upper mold 91 is split in thelongitudinal direction. That is, in the upper mold 91, a splittingposition BL is set in the longitudinal direction at the center in thewidth direction. The upper mold 91 is split at the splitting position BLinto two pieces of one side and the other side with respect to the widthdirection, that is, the upper mold 91 is split into two upper molds 91Aand 91B. The splitting position BL of the upper mold 91 is set at aposition passing through a forming position 91 t, which will be referredto as an end portion forming position hereinafter, for forming the endportion 51 t (shown in FIG. 4C) on the outer circumferential side in theinner and outer circumferential direction of the infinite circulatingpassage 28 in the spacer portion 51.

As shown in FIG. 7, in this metallic mold 90, gates 94 for pouringmelted synthetic resin into the product configuration portions 93 areprovided in the lower mold 92. A necessary number of gates 94 areprovided at positions corresponding to the end portion on the innercircumferential side of the spacer portion 51 to be formed. In theexample shown in the drawing, the gates are provided every two spacerportions 51 apart. On the upper mold 91 side, a plurality of pushingpins 95 are provided. These pushing pins 95 are arranged being opposedto wide portions of the connecting arm portions 52 connecting the spaceportions 51, that is, these pushing pins 95 are arranged being opposedto peripheries of portions connecting the spacer portions 51 with theconnecting arm portions 52. In this connection, the pushing pins 95 arearranged on a side having the product configuration portion 93 on theside on which the balls 46 are allowed to move in the upper mold 91 andthe lower mold 92.

The manufacturing step is conducted by the above metallic mold 90 asfollows. First, the two split upper molds 91A and 91B are combined witheach other into the upper mold 91. Then, as shown in FIG. 7A, the uppermold 91 and the lower mold 92 are respectively arranged at predeterminedpositions being opposed to each other. Next, as shown in FIG. 7B, theupper mold 91 is moved downward so as to make the upper mold 91 and thelower mold 92 tightly come close to each other at a predeterminedopposing position. Next, as shown in FIG. 7C, melted synthetic resin isinjected from the gates 94, which are arranged in the lower mold 92,into the product configuration portions 93. Next, after the injectedsynthetic resin has been solidified, as shown in FIG. 7(d), the uppermold 91 is moved upward so as to open the mold in the verticaldirection. Then, by the pushing pins 95 arranged on the upper mold 91side, the thus formed rolling element accommodating belt 50 is pushedout and picked up. In this way, the rolling element accommodating belt50 described above can be manufactured. Therefore, in the end portion 51t of the spacer portion 51 on the rolling element accommodating belt 50,a trace of the parting line of the metallic mold 90 is formed.

Next, actions and advantages of the above metallic mold 90, the rollingelement accommodating belt 50 manufactured by this metallic mold 90 andthe linear guide 10 having this rolling element accommodating belt 50will be explained below.

According to the above metallic mold 90, the splitting position BL ofthe metallic mold is set at a position passing through the end portionforming position 91 t of the upper mold 91. Therefore, a joint portionof this splitting position BL can be made to function as a gas vent.

Next, appropriately referring to FIGS. 8 and 9, advantages of the abovesplitting structure will be explained in detail as follows. In thiscase, FIG. 9 is a schematic illustration for explaining a metallic moldof Comparative Example. Compared with the upper mold 91 of the presentembodiment described before, the upper mold 91H of Comparative Exampleshown in FIG. 9A does not include a splitting structure (splittingposition BL) composed in the longitudinal direction. Only at this point,the upper mold 91H of Comparative Example is different from the uppermold 91 of the present embodiment. Concerning this matter, refer to FIG.9A. FIG. 9B is a view showing a model of the flow of resin when meltedresin is injected into the product configuration portion 93H of themetallic mold 90H in which the upper mold 91H is combined with the lowermold 92. In this connection, in FIGS. 8A and 9B, an arrow indicated bythe reference mark A shows an image of the flow of resin in the productconfiguration portion 93. An arrow indicated by the reference mark Bshows an image of the flow of gas discharging from the joint portionbetween the upper mold 91 and the lower mold 92. An arrow indicated bythe reference mark C shows an image of the flow of gas discharging fromthe joint portion (splitting position BL) between the split upper molds91A and 91B.

As described before, in the product configuration portion, in theneighborhood of the forward end portion of the resin flow, residual airor gas, which is generated by melting the resin material, stays. InComparative Example, as shown in FIG. 9B, at the end portion formingposition 91 t at which the resin flow comes to a dead end, air or gastends to stay. It is impossible for melted resin to sufficiently enterthis portion in which air or gas is staying. Therefore, in the case ofthe upper mold 91H having no splitting structure in the longitudinaldirection, the underfill portion Kn of resin tends to be generated atthe end portion 51 t of the spacer portion 51 of the product obtained inthis way as shown in FIG. 9C. This underfill portion Kn of resin can bea cause of damaging the rolling element accommodating belt 50.

On the other hand, in the case of the metallic mold 90 of the presentembodiment described before, the joint portion of the splitting positionBL, at which the upper mold 91 is split in the longitudinal direction,can be made to function as a gas vent. Therefore, as shown in FIG. 8A,gas can be discharged from this splitting position BL. Especially, it ispossible to prevent or suppress gas from staying in the end portionforming position 91 t at which gas tends to stay. Due to the foregoing,melted resin can reach the end portion 51 t which is a forward endportion of the spacer portion 51. Accordingly, the generation of theunderfill portion of resin can be prevented at the time of forming.

According to this metallic mold 90, after the completion of forming therolling element accommodating belt 50 in the metallic mold 90, when therolling element accommodating belt 50 is pushed with the pushing pins 95from a side on which the balls 46 accommodated in the rolling elementaccommodating portion 59 are allowed to move, the rolling elementaccommodating belt 50 can be released from the mold on the side on whichno under-cut is formed. Accordingly, the rolling element accommodatingbelt 50 can be released from the mold without being given an extremelystrong force. Since no under-cut is formed, the metallic mold 90 can beeasily manufactured. The splitting portion (parting line) PL, which istransferred onto the rolling element accommodating belt 50 formed by themetallic mold 90 of the present embodiment, is formed by the verticalline PL1 formed along the releasing line at the center in the widthdirection of each spacer portion 51 and by the line PL2 which appears atthe splitting position of the upper mold 91 and the lower mold 92 andpasses through a boundary between the forward end portion of theinclined face portion 56 a and the no-contact face 55 and is formedalong the inner circumferential face of the ball accommodating hole 58as shown by the bold solid line in FIG. 8 B.

According to the rolling element accommodating belt 50 described above,since it is manufactured with this metallic mold 90, the generation ofthe underfill portion Kn, which is caused in the forward end portion ofthe spacer portion 51 at the time of forming, can be suitably preventedor suppressed and a desired molding product can be formed. Due to theforegoing, it is possible to positively ensure a predeterminedperformance in which the balls 46 are smoothly circulated as a row ofrolling elements 62 in the infinite circulating passage 28 whilepredetermined intervals are being maintained between the balls 46.

On this rolling element accommodating belt 50, the rolling elementaccommodating portions 59 for individually accommodating the balls 46are defined by the spacer portions 51 and the connecting arm portions52. These rolling element accommodating portions 59 are formed so thatthe balls 46 accommodated there can be allowed to move to the outercircumferential side in the inner and outer circumferential direction ofthe infinite circulating passage 28. Therefore, when the balls 46 areincorporated onto the rolling element accommodating belt 50, the balls46 can be easily inserted into the rolling element accommodatingportions 59 from the side on which the balls 46 to be accommodated areallowed to move.

Further, according to the linear guide 10 described before, since thisrolling element accommodating belt 50 is provided, there is a lowpossibility of the occurrence of damage of the rolling elementaccommodating belt 50 caused by the underfill Kn of resin. Therefore,the quality of the rolling element accommodating belt 50 can bestabilized.

As explained above, according to the metallic mold 90 of the invention,an obstruction caused to the arrival of the melted resin at the endportion of the product configuration portion 93 caused by the gasstaying there can be prevented or suppressed. Therefore, it is possibleto obtain a desired rolling element accommodating belt 50 having nounderfill portion Kn of resin. It is possible to provide the rollingelement accommodating belt 50. It is also possible to provide the linearguide 10 having the rolling element accommodating belt 50.

In this connection, the metallic mold for manufacturing a rollingelement accommodating belt, the rolling element accommodating belt for alinear guide apparatus and the linear guide apparatus of the presentinvention are not limited to the above specific embodiments.Modifications can be made without departing from the spirit and scope ofthe present invention.

For example, in the embodiment described above, the linear guide havingballs is exemplarily explained as an embodiment of the metallic mold,the rolling element accommodating belt and the linear guide apparatushaving the rolling element accommodating belt. However, the presentinvention is not limited to the above specific embodiment. For example,it is possible to apply the present invention to a roller guide havingrollers.

For example, in the embodiment described above, the above rollingelement accommodating portions 59 are formed so the balls 46accommodated there can be allowed to move onto the outer circumferentialside in the inner and the outer circumferential direction in theinfinite circulating passage 28. However, the present invention is notlimited to the above specific embodiment. In order to provide astructure in which releasing is conducted without giving an extremelystrong force to the rolling element accommodating belt, the rollingelement accommodating portion may be composed so that the rollingelements accommodated there can be allowed to move at least to one sidein the inner and the outer circumferential direction of the infinitecirculating passage. Due to the above structure, after the completion offorming the rolling element accommodating belt in the metallic mold,when the rolling element accommodating belt are pushed with the pushingpins from the side on which the rolling elements are allowed to move,the rolling element accommodating belt can be smoothly released from theside on which no under-cut is formed.

Concerning the metallic mold having a splitting structure of the presentinvention, the present invention is not limited to the above specificembodiment. When at least one of the upper mold 91 and the lower mold 92has a splitting structure and the splitting structure is composed insuch a manner that the splitting position BL is set at a positionpassing through a position where an end portion on at least one side inthe inner and outer circumferential direction of the infinitecirculating passage 28 of the spacer portion 51 is formed, it ispossible to prevent or suppress the generation of the underfill portionof resin in the forward end portion of the spacer portion 51 at the timeof forming.

For example, the first modification is shown in FIG. 10.

As shown in FIG. 10, this first modification is different from theembodiment described before at the point that the lower mold 92, whichis a stationary mold, is also split. That is, in the same manner as thatof the upper mold 91 of the above embodiment, this lower mold 92 has asplitting structure in which the mold is split in the longitudinaldirection and the splitting position BL2 is set at the center in thewidth direction in the longitudinal direction and the mold is split intotwo split molds 92A and 92B, wherein one mold is located on one side inthe width direction of the splitting position BL2 and the other islocated on the other side. The splitting position BL2 of the lower mold92 is set at a position passing through a position 92 n at which the endportion 51 n (shown in FIG. 5C) on the inner circumferential side in theinner and outer circumferential direction of the infinite circulatingpassage 28 of the spacer portion 51 is formed.

According to the above structure, in addition to the action andadvantage of the embodiment described before, even in the lower mold 92,the generation of the underfill Kn of resin in the end portion 51 n onthe inner circumferential side of the spacer portion 51 can bepositively prevented. However, in the same manner as that of thestructure of the embodiment described before, the splitting position ofthe upper mold 91 and the lower mold 92 is located close to the lowermold 92. Therefore, in the case where the end portion 51 n on the innercircumferential side of the spacer portion 51 is located in theneighborhood of the lower mold 92, like the metallic mold 90 of theembodiment described above as compared with the end portion formingposition 91 t formed on the upper mold 91 side, it is formed on thelower mold 92 side. Gas can easily discharge from the position 92 nwhich forms the end portion 51 n on the inner circumferential side ofthe spacer portion 51. Therefore, it is unnecessary to positively splitthe lower mold 92, too. When the lower mold 92 is split, the structureof the metallic mold 90 becomes complicated, which raises themanufacturing cost of the metallic mold 90. Therefore, in the aboveembodiment, they attach importance to a reduction of the manufacturingcost and employ the structure in which the lower mold 92 is not split.

For example, FIGS. 11 and 12 show the second modification.

As shown in FIG. 11, the second modification is different from theembodiment described before at the following point. Instead of thesplitting position BL in the embodiment described before, in the uppermold 91J, at the respective positions of the recess portions 91 c forforming the spacer portions 51, the splitting position BL3 is set in adirection perpendicular to the longitudinal direction. That is, thisupper mold 91J has the splitting structure in the directionperpendicular to the longitudinal direction and is split correspondingto the number of the spacer portions 51. The splitting position BL3 ofthis upper mold 91J is set at a position passing through the end portionforming position 91 t for forming the end portion 51 t (shown in FIG.5C) on the outer circumferential side in the inner and outercircumferential direction of the infinite circulating passage 28 of thespacer portion 51.

Even in this structure, a joint portion of the splitting position BL3can be made to function as a gas vent. Therefore, the generation of theunderfill of resin in the end portion 51 t on the outer circumferentialside of the spacer portion 51 can be prevented or suppressed.

Since the number of the split molds is increased in the secondmodification, the structure becomes complicated. However, the secondmodification is advantageous in that no split face of splitting themetallic mold is provided on the contact face 56 of the rolling elementaccommodating belt 50. That is, there is no possibility that burr isgenerated on the contact face 56 coming into contact with the ball 46which is a rolling element. Therefore, this structure is advantageous inthat the ball 46 and the rolling element accommodating belt 50 arestably contacted with each other. In this connection, as shown by a boldsolid line in FIG. 12, the splitting position (parting line) PL ofsplitting the metallic mold transferred onto the rolling elementaccommodating belt formed by the metallic mold of the secondmodification is formed by the line PL3, which is formed in a directionperpendicular to the longitudinal direction in the spacer portion 51,and by the line PL2 which appears at the splitting position of the uppermold 91 and the lower mold 92 and passes through a boundary between theforward end portion of the inclined face portion 56 a and the no-contactface 55 and is formed along the inner circumferential face of the ballaccommodating hole 58.

Second Embodiment

Next, the second and third embodiment according to the sixth to eleventhaspect of the invention will be explained.

The basic constitution of the rolling element accommodation belt, thelinear guide apparatus and the metallic mold are the same, the detailedexplanation regarding the similar members will be omitted.

As shown in FIGS. 13B and 13C, a dividing position PL, at which theproduct configuration portions 193 of the upper mold 191 and the lowermold 192 are divided from each other, is set at a position which is aboundary between the non-contact face 155 and the contact face 156 ofeach spacer portion 151. As shown in FIG. 14, in this metallic mold 190,gates 194 for pouring melted synthetic resin into the productconfiguration portions 193 are provided in the lower mold 192. Anecessary number of gates 194 are provided at positions corresponding tothe end portion on the inner circumferential side of the spacer portion151 to be formed. In the example shown in the drawing, the gates areprovided every two spacer portions 151 apart. On the upper mold 191side, a plurality of pushing pins 195 are provided. These pushing pins195 are arranged being opposed to wide portions of the connecting armportions 152 connecting the space portions 151, that is, these pushingpins 195 are arranged being opposed to peripheries of portionsconnecting the spacer portions 151 with the connecting arm portions 152.In this case, the pushing pins 195 are arranged on a side having theproduct configuration portions 193 on the side to allow the balls 146 tobe moved of the upper mold 191 and the lower mold 192.

The manufacturing step executed by this metallic mold 190 is describedas follows. As shown in FIG. 14A, the upper mold 191 and the lower mold192 are respectively arranged at predetermined positions being opposedto each other. Next, as shown in FIG. 14B, the upper mold 191 is moveddownward so as to make the upper mold 191 and the lower mold 192 tightlycome close to each other at a predetermined opposing position. Next, asshown in FIG. 14C, melted synthetic resin is injected from the gates194, which are arranged in the lower mold 192, into the productconfiguration portions 193. Next, after the injected synthetic resin hasbeen solidified, as shown in FIG. 14D, the upper mold 191 is movedupward so as to open the mold in the vertical direction. Then, by thepushing pins 195 arranged on the upper mold 191 side, the thus formedrolling element accommodating belt 150 is pushed out and picked up. Inthis way, the rolling element accommodating belt 150 described above canbe manufactured. In this case, the dividing position PL, at which theupper mold 191 and the lower mold 192 are divided from each other, islocated at the boundary between the non-contact face 155 and the contactface 156 of each spacer portion 151. Therefore, as shown in FIG. 15, onthe thus formed rolling element accommodating belt 150, a dividing linePL′ is formed on the boundary between the non-contact face 155 and thecontact face 156 of each spacer portion 151.

Next, actions and advantages of the rolling element accommodating belt150 and the linear guide 110 will be explained below.

In the thus composed linear guide 110, when the slider 116 is relativelymoved in the axial direction of the guide rail 112 while the balls 146are rolling in the infinite circulating passage 128, the rolling elementaccommodating belt 150 is also moved in the infinite circulating passage128 together with the balls 146. At this time, in the infinitecirculating passage 128, the spacer portion 151 of the rolling elementaccommodating belt 150 pushes the ball 146 located in the front in themoving direction. Further, the ball 146 pushes the spacer portion 151located in the front in the moving direction. Due to the foregoing, theentire rolling element row 162 circulates in the infinite circulatingpassage 128. The rolling element row 162 is moved in the oppositedirection to the slider 116 in the rolling element passage 126. Therolling element row 162 enters from one end portion of the rollingelement passage 126 into one direction changing passage 124 so that themoving direction of the rolling element row 162 can be changed. Therolling element row 162 enters from the direction changing passage 124into the rolling element return passage 120 and moves in the samedirection as that of the slider 116. The rolling element row 162 entersinto the other direction changing passage 124 so that the movingdirection can be changed again. Then, the rolling element row 162returns to the rolling element passage 126. The above circulation of therolling element row 162 can be repeated.

According to this linear guide 110, in the infinite circulating passage128, the spacer portions 151 are interposed between the balls 146.Therefore, the balls 146 are not directly contacted with each other.Accordingly, it is possible to prevent the generation of noise andabrasion caused when the balls 146 rub each other. The spacer portions151 are connected to each other by the connecting arm portions 152 sothat the rolling element accommodating belt 150 can be composed.Therefore, while the balls 146 are maintaining predetermined intervals,the rolling element row 162 can be smoothly circulated in the infinitecirculating passage 128.

According to this linear guide 110, the connecting arm portion 152 ofeach rolling element accommodating belt 150 is engaged with the guidegroove 160. Therefore, it is possible to prevent each spacer portion 151from falling down in the rolling element passage 126. Further, it ispossible to prevent an arrangement of the rolling element row 162 frombeing disturbed, that is, it is possible to prevent a smooth movement ofthe rolling element row 162 from being obstructed. Since the connectingarm portion 152 of the rolling element accommodating belt 150 is guidedby the infinite circulating passage 128 along the guide groove 160,deviation of the rolling element accommodating belt 150 is restrictedwhile it is moving. Further, deviation of the ball 146 held between theconnecting arm portions 152 of the rolling element accommodating belt150 is also restricted. Therefore, the entire rolling element row 162can be accurately, smoothly moved in the infinite circulating passage128.

Further, according to this linear guide 110, the face 154 of the spacerportion 151 of the rolling element accommodating belt 150 directed tothe adjacent ball 146 side includes: a non-contact face 155 which is notcontacted with the adjacent ball 146; and a contact face 156 having aportion which is contacted with the adjacent ball 146. The dividingposition PL, at which the product configuration portions (cavities) 193of the upper mold 191 and the lower mold 192 are divided, is located onthe boundary between the non-contact face 155 and the contact face 156of each spacer portion 151. Therefore, with respect to the peripheraledge portion of the spacer portion 151 and with respect to the contactface 156 having a portion coming into contact with the ball 146, therolling element accommodating belt 150 can be composed without providingthe dividing line PL′ of the metallic mold.

Therefore, in the case of this rolling element accommodating belt 150,even in the case where burr is generated in the portion of the dividingline PL′ corresponding to the dividing position PL of the joint portionof the metallic mold 190, the burr can be prevented or suppressed frombeing rubbed on the inner circumferential wall of the infinitecirculating passage 128 and the burr can be also prevented from beinghooked on the inner circumferential wall. Further, the contact face 156,which is a face to be contacted with the ball 146, and the ball 146 canbe stably contacted with each other. Therefore, according to this linearguide 110, even when burr is generated, the rolling elementaccommodating belt 150 can be smoothly circulated. When countermeasuresare taken in order to prevent the generation of burr, it is possible tomitigate the degree of enhancing the accuracy of the joint portion ofthe metallic mold 190. It is also possible to mitigate the degree ofcontrolling the forming condition. Therefore, the manufacturing cost canbe reduced.

According to this linear guide 110, on the rolling element accommodatingbelt 150, the non-contact face 155 of each spacer portion 151 is formedon a plane in a direction perpendicular to the alignment direction inthe infinite circulating passage 128. Therefore, when a releasingdirection of the upper mold 191 and the lower mold 192 is set in thedirection in which the non-contact face 155 is formed, releasing can beeasily executed.

Further, according to this linear guide 110, by the spacer portion 151and the connecting arm portion 152, the rolling element accommodatingportion 159 for accommodating each ball 146 is defined. This rollingelement accommodating portion 159 is composed so that the ball 146accommodated there can be allowed to move to the outer circumferentialside in the circumferential direction of the infinite circulatingpassage 128. Due to the above structure, when the rolling elementaccommodating belt 150 is pushed with a pushing pin 195 from a side onwhich the rolling elements 46 are allowed to move after the rollingelement accommodating belt 150 has been formed in the metallic mold 190,it is possible to release the rolling element accommodating belt from aside on which no undercut is formed. Therefore, releasing can beconducted without giving an extremely strong force to the rollingelement accommodating belt 150. Since no undercut portion is formed, themetallic mold 190 can be easily manufactured.

Third Embodiment

Next, the third embodiment of the present invention will be explainedbelow. In this connection, the third embodiment is different from thesecond embodiment only in the structure of the rolling elementaccommodating belt. Other points of the third embodiment are the same asthose of the second embodiment. Therefore, only the different point isexplained and other points are omitted here.

As shown in FIG. 16, in the case of the rolling element accommodatingbelt 150B of the third embodiment, both faces of the contact face 156Bof the spacer portion 151 are formed into shapes by which the balls 146can be restricted in the directions of the surface side and the backside of the infinite circulating passage 128. This point is differentfrom the second embodiment explained before.

As the structure is shown in detail in FIG. 16A, the face 154B of thespacer portion 151 directed to the side of the adjacent ball 146 has acontact face 156B on which the inclined face portion 156 a, which iscomposed of a concave conical face, is respectively formed on the innerand the outer circumferential side of the infinite circulating passage128. Between both the inclined face portions 156 a on the inner and theouter circumferential side, a short plane portion 156 c connecting theupper and the lower inclined face portion 156 a is provided.

Even in the above structure, according to this rolling elementaccommodating belt 150B, in the same manner as that of the secondembodiment, when the dividing position PL, at which the productconfiguration portions (cavities) 193 of the upper mold 191 and thelower mold 192 are divided, is set at the non-contact face 155 or at theboundary between the non-contact face 155 and the contact face 156, withrespect to the peripheral edge portion of the spacer portion 151 andwith respect to the contact face 156 having a portion coming intocontact with the ball 146, the rolling element accommodating belt 150Bcan be composed without forming the dividing line PL′ of the metallicmold 190. Accordingly, even in the case where burr is generated, therolling element accommodating belt 150B can be smoothly circulated. Inthis connection, in the example shown in FIG. 16B, the dividing positionPL, at which the upper mold 191 and the lower mold 192 are divided, isset so that the dividing line PL′ can be formed on the boundary betweenthe non-contact face 155 and the contact face 156. In the case of thisthird embodiment, undercut is formed. Therefore, when the rollingelement accommodating belt is picked up from the metallic mold 190B, itis necessary to forcibly push out it with the pushing pins 195.

In the structure of this third embodiment, both sides of the contactface 156B of the spacer portion 151 restrict the ball 146 in thedirections of the surface side and the back side of the infinitecirculating passage 128. Accordingly, when the balls 146 have been onceincorporated onto the rolling element accommodating belt 150B, the balls146 seldom fall off. Therefore, this structure is advantageous at thetime of storage and conveyance.

As explained above, according to the rolling element accommodating belts150, 150B and the linear guide 110 provided with the rolling elementaccommodating belts 150, 150B, even when burr is generated, the rollingelement accommodating belts 150, 150B can be smoothly circulated.

In this connection, the rolling element accommodating belt for a linearguide apparatus and the linear guide apparatus of the present inventionare not limited to the above specific embodiments. Modifications can bemade without departing from the spirit and scope of the presentinvention.

For example, in the embodiments described above, as an embodiment of thelinear guide apparatus having the rolling element accommodating belt ofthe present invention, the linear guide having balls has been explainedbefore. However, the present invention is not limited to the abovespecific example. For example, the present invention can be applied to aroller guide having rollers.

For example, in the second embodiment described above, the rollingelement accommodating portion 159 is composed so that the ball 146accommodated there can be allowed to move to the outer circumferentialside in the circumferential direction of the infinite circulatingpassage 128. However, the present invention is not limited to the abovespecific embodiment. In order to compose the rolling elementaccommodating belt so that an extremely strong force can not be given tothe rolling element accommodating belt at the time of releasing, therolling element accommodating portion may be composed so that therolling element accommodated there can be allowed to move at least toone side in the circumferential direction of the infinite circulatingpassage. Due to the above structure, after the rolling elementaccommodating belt has been formed in the metallic mold, when therolling element accommodating belt is pushed with the pushing pins fromthe side on which the rolling element is allowed to move, the rollingelement accommodating belt can be smoothly released from the side onwhich no undercut is formed.

For example, in the second embodiment described above, the dividingposition PL, at which the product configuration portions 193 of theupper mold 191 and the lower mold 192 are divided, is located on theboundary of the non-contact face 155 and the contact face 156 of eachspacer portion 151. However, the present invention is not limited to theabove specific embodiment. For example, the dividing position PL may belocated at the position of the non-contact face 155. Even in thisstructure, the rolling element accommodating belt 150 can be composedwithout forming the dividing line PL′ of the metallic mold 190 withrespect to the circumferential edge portion of the spacer portion 151and with respect to the contact face 156 having the portion coming intocontact with the ball 146. In this connection, in order to simplify thestructure of the upper mold 191 and the lower mold 192, it is preferablethat the dividing position PL of the upper mold 191 and the lower mold192 is located on the boundary of the non-contact face 155 and thecontact face 156 and that the rolling element accommodating belt 150 isformed by setting the dividing line PL′ on the boundary of thenon-contact face 155 and the contact face 156.

While the invention has been described in connection with the exemplaryembodiments, it will be obvious to those skilled in the art that variouschanges and modification may be made therein without departing from thepresent invention, and it is aimed, therefore, to cover in the appendedclaim all such changes and modifications as fall within the true spiritand scope of the present invention.

1. A metallic mold for injection molding a rolling element accommodatingbelt for a linear guide apparatus, which has an infinite circulatingpassage in which a plurality of rolling elements are rolling andcirculating, the rolling element accommodating belt comprising: a spacerportion interposed between the rolling elements adjacent to each other;and a connecting arm portion for connecting the spacer portions to eachother, wherein the rolling elements are aligned in the infinitecirculating passage in an alignment direction, the metallic moldcomprising: an upper mold; a lower mold; and a product configurationportion provided between the upper mold and the lower mold, wherein therolling element accommodation belt is molded within the productconfiguration portion, and at least one of the upper and the lower moldhas a splitting structure in which a splitting position is located at aposition where an end portion of at least one side of inner and outercircumferential direction of the infinite circulating passage of thespacer portion is formed.
 2. A rolling element accommodating beltmanufactured by the metallic mold according to claim
 1. 3. A rollingelement accommodating belt for a linear guide apparatus, which has aninfinite circulating passage in which a plurality of rolling elementsare rolling and circulating, the rolling element accommodating beltcomprising: a spacer portion interposed between the rolling elementsadjacent to each other; and a connecting arm portion for connecting thespacer portions to each other, wherein the rolling elements are alignedin the infinite circulating passage in an alignment direction, therolling element accommodation belt is formed by injection molding byusing a metallic mold having splitting structure, and a parting line ofthe metallic mold is transferred to an end portion on at least one sideof inner and outer circumferential direction of the infinite circulatingpassage in the spacer portion.
 4. A linear guide apparatus comprisingthe rolling element accommodating belt according to claim
 1. 5. A linearguide apparatus comprising the rolling element accommodating beltaccording to claim
 2. 6. A rolling element accommodating belt for alinear guide apparatus, which has an infinite circulating passage inwhich a plurality of rolling elements are rolling and circulating, therolling element accommodating belt comprising: a spacer portioninterposed between the rolling elements adjacent to each other; and aconnecting arm portion for connecting the spacer portions to each other,wherein the rolling elements are aligned in the infinite circulatingpassage in an alignment direction, and a face of each spacer portiondirected to the rolling element comprises: a non-contact face which doesnot contact with the rolling element; and a contact face which is hollowwith respect to the non-contact face and contacts with the rollingelement.
 7. The rolling element accommodating belt according to claim 6,wherein the non-contact face is formed of a plane perpendicular to thealignment direction in the infinite circulating passage.
 8. The rollingelement accommodating belt according to claim 6, wherein rolling elementaccommodating portions for individually accommodating the rollingelements are defined by the spacer portions and the connecting armportions, and the rolling element accommodating portions are formed sothat the accommodated rolling elements is allowed to move to at leastone side in the inner and the outer circumferential direction of theinfinite circulating passage.
 9. The rolling element accommodating beltaccording to claim 6, wherein the rolling element accommodating belt ismanufactured by an injection molding by using a metallic mold comprisinga product configuration portion formed between an upper mold and a lowermold, and a dividing line between the upper mold and the lower mold isformed on the non-contact face of the spacer portion or on a boundarybetween the non-contact face and the contact face.
 10. A linear guideapparatus comprising a rolling element accommodating belt according toclaim
 6. 11. A metallic mold for manufacturing the rolling elementaccommodating belt according to claim 6 by injection molding, themetallic mold comprising: an upper mold; and a lower mold, wherein aproduct configuration portion for forming the rolling elementaccommodating belt is formed between the upper mold and the lower mold,and the upper mold and the lower mold are divided on a position wherethe non-contact face of the spacer portion or on a boundary between thenon-contact face and the contact face is formed.